This is an extreme filter. Pure rock and roll. Doepfer has created a beautifully distorting nonlinear monster, inspired by the Korg MS-20 filters (a 6 dB highpass and a 12 dB lowpass filter). Both HP and LP modes are available simultaneously (via normalized input jacks). The “real deal” however will need two A-106-1 filters: this allows for independent filter frequencies for HP and LP.
We start with the usual three A-110 VCOs (all saw outputs, one of them transposed 1 oct down), go into the first A-116-1 (using highpass mode) and then into the second A-106-1 (using lowpass mode). Pitch and ADSR trigger are controlled by an A-155 seqencer. Different clipping levels were used (manual control). For technical details of the A-106-1 Xtreme Filter take a look at Doepfer’s Homepage:
During the first 2 minutes, only a single A-106-1 is used, then we switch to two (HP first, then LP) filters. Here we go with the example sound: